Ansys Fluent Working Very Slow.

- October 31, 2017 at 10:40 pm
  
  Ahmed
  Subscriber
  
  I recently downloaded Ansys Student 18.2 . I have been solving very basic fluid dynamics problems which may require 200 or 300 iterations at most to converge to the desired tolerance. However , my Ansys fluent software is working very slowly and is taking a lot of time to do the iterations. For instance to do 300 iterations it took close to one hour. My laptop has Intel Core i5 -2430M with 8GB Ram. A friend of mine who has the same processor on his laptop did the same problem on Ansys. He was able to do 300 iterations in 7.111s.
  
  I would also like to mention that once when I started my laptop and opened Ansys Fluent; it worked properly. It performed all the solutions in a matter of seconds. However this was a one time occurrence; when I restarted my laptop ; Ansys Fluent went back to performing slowly.
  
  I would be really grateful if someone could look into this matter.
  
  Thank you.
- November 1, 2017 at 9:41 am
  
  Raef.Kobeissi
  Subscriber
  
  Hello 300 iteration within 7 seconds under the specs you mentioned sounds impossible to me even if the model was 2D. Could you please provide a description of the model you were running.
  I believe if the number of elelments is high in your model, an hour would make sense for 300 iterations on a PC similar to what you’ve described.
  Cheers
- November 1, 2017 at 3:09 pm
  
  Ahmed
  Subscriber
  
  Thanks for your response.
  
  I was running a simulation on a 2-D model with 4000 cells.I was simulating laminar flow in a channel. Since I just started using Ansys I mainly used default settings for all other other parameters except I just altered the inlet velocity magnitude. My tolerance specification was 10^-5 for velocity and momentum equations. My PC has Intel Core i5 -2430M with 8GB Ram and with in built graphic card ; Intel HD Graphics 3000.
  
  Let me know if you any need any further information. Thanks.
- November 1, 2017 at 5:38 pm
  
  Ahmed
  Subscriber
  
  Update:
  
  I restarted my Laptop and opened Ansys Fluent. it worked properly this time. I performed 1000 iterations in 27 seconds. Later, I restarted my laptop and opened Ansys Fluent again and it went back to performing slowly. However this time I copied the messages that appeared in the console tab in both slow and fast cases. All the messages were same except the following.
  
  Slow Case:
  
  Multicore SMT processors detected. Processor affinity set!
  
  Fast Case:
  
  DESKTOP-621A36I is already loaded (23.9042%). Process affinity not being set.
  
  I hope this helps you with your diagnosis.
  
  Thank you